434 IMMUNOLOGY 



4. Neisser maintains that the refractory stage or immunity to 

 reinoculation is evidence of an existing infection, but Chesney 

 (1927) concludes that a definite immunity persists after the body 

 is free of infectious agents. 



5. Clinical evidence indicates that reinfection is rarely ob- 

 served. This question is also discussed by Cannon (1933) in a 

 report of a case of reinfection. 



6. A number of syphilologists hold that antibodies do not seem 

 to play a role in acquired immunity to Treponema pallidum. Two 

 mechanisms are suggested by Neisser. One of these is a condition 

 of cellular indifference to the presence of the spirochetes. This 

 phenomenon he has named ''anergy." The second is a state of 

 allergy or hypersensitivity that may function in the body 's defense. 



7. There is some controversy over the role of phagocytosis in 

 immunity to Treponema pallidum. Chesney (1927) cites the in- 

 vestigations of both Ehrmann and Levaditi who report having 

 observed phagocytosis of Treponema pallidum in stained sections. 

 Both Zinsser (1939) and Chesney (1927) suggest that perhaps 

 the reticulo-endothelial system may play a role in acquired im- 

 munity in syphilis. 



Nonspecific Wassermann Reactions. — It is generally admitted 

 that false positive Wassermann reactions may occur in such con- 

 ditions as acute infectious mononucleosis, malaria, leprosy and 

 perhaps a few other diseases. Landsteiner and Van der Scheer 

 (1927) say that it is known that rabbits infected with trypanosomes 

 develop positive Wassermann reactions. They report that similar 

 positive results were obtained by injecting dead trypanosomes into 

 rabbits. 



Kemp, Fitzgerald and Shepard (1940) iiave summarized the 

 literature bearing upon the occurrence of positive serological tests 

 for syphilis in animals other than man. It is evident that positive 

 serological tests, especially flocculation tests, are of frequent occur- 

 rence in many species of animals. Their blood contains a normal 

 biologic reagin. 



Whether genuine nonspecific reactions occur in man has been the 

 object of a recent survey by the United States Public Health 

 Service. Eagle (1941) summarizes the results of this study in- 

 volving 40,545 initial specimens taken from as many college stu- 

 dents representing twenty-five schools. All specimens giving posi- 



